Protected metal and process of making it



Sept. l, 1925.

F. F. FOWLE ET AL PROTECTED METAL AND PRocEss oF MAKING 1T` 2. Tm s Sw. All

.N NJN Patented Sept. l, 1.925. l,

UNITED STA 'ras IPl'rlazlar OFFICE."

ERANx E. rowLE, E xENILwoRTH, ILLINoIs, AND EaEDEaIex u. cnAro, or

MUNCIE,

INDIANA.

I `rRoTECTED METAL AND raocEss or MAKING IT.

Application IedDecember 18, 1923. Serial No. 681,435.

to improve the zinc-coating of iron and low- A carbon steel articles, especially of iron yand steel wire. More specifically, such primary object is to produce a zinc-coatedartmle, especially iron or low-carbon steel wire, the

coating of which will adhere firmly and will not peel or Hake 0E even? when subjected to sharp bends or twists, as for example upon wrapping such a wire around its own diameter; and es ecially to accomplish all this effectively wit iron or low-carbon steel.

It is our further object to get this imroved zinc-coating without substantially Impairing the mechanical and electrical properties of such coated articles, especially wire, such as tensile strength, elongation andelectrical resistivity.

Still another object of our invention is to produce a more satisfactory and enduring zinc-coating with a smaller quantity of zinc.

In accomplishing these results, from the standpoint of zinc-coating, we first coat the iron-base article, such,..as ironnr lowecarbon steel wire, advantageouslyl before it has been drawn to finished size, with a thin layer or film of relatively high-carbon steel; and subsequently apply the zinc coating. The first coating or jacket of relatively high-carbon steel vis a binder, and serves to improve the bond between the iron or low-carbon steel core and the zinc coating.

We recognize as prior art the co-pending application of one of us, Frederick M. Crapo, Ser. No. 679,650, filed Dec, 10, 1923, now

Patent No. 1,501,887, granted Julyv 15, 1924.-

We also recognize as independent inventions of said Frederick M. Crapo certain things specificallv claimed by 'hi-m'in certain co-pend-ing applications filed by him, as follows:

Serial No. 695,423, filed February 27, 1924;

Serial No. 712,000, filed May 9, 1924; and

Serial-No.A` 744,976, filed October l21, 1924.'

The accompanying drawings illustrate our invention: Fig. 1 is a greatly magnified fragmentalcross-section of ay wire coated vin a'c-` cordance with our invention; Fig. 2 is a more hi ghlyv magnified fragmental cross-section of such wire, to indicate thel alloy films formed in 'the coating process; Fig. 3fis a vertical section through an ingot mold in which the steel coating is obtained by pouring molten steel around an iron core; Flg. 4 is a vertical section through an ingot mold in which the coating of steel o-n the iron core is obtained by pouring the moltenl iron within 'a steel-tube which lines "the-"mold and eveni tually forms the jacket orcoatingof the in got; Figs. 5 and 6 `are vertical, sections through a bath of molten steel for steelcoating dipped-in ingots and wire respectively; and Fig. 7 is a diagrammatic view illustrating the generall sequence of operations on a steel-coated billet to produce a zinc-coated wire therefrom.

The essence of our invention is a plurality of coatings on an iron-base (or ferrous metal) article 10, especially iron or lowcarbon steel, chief in which are a coating or jacket of relatively high-carbon steel 11 and a coating of zinc 12, applied and existing in the order named; as is shown in Fig. 1.

We recognize that in the process of applying the high-carbon steel coating, and in the hot-process of applying the zinc coating, intermediate' coatings or films of alloy of the coated metal and the coating material inherently will be formed` and will exist in "the final'product; as is "illustrated in Fig. 2.

For example, there will be an intermediate alloy film 13 of iron. anfdsteel, or of lowcarbon steel and high-carbon steel, between the primary iron-base body and the highcarbon steel coating; and there may be present a -pluralityl of such intermediate alloy films, graduated in composition ,from the constituents, of the irnbase bod to the constituents of the steel coating.' ike- Wise there will be an intermediate coating or alloy film 14, between the high-carbon steel coating and the zinc coating, comprising an alloy of Isteel and zinc, or of iron, steel and zinc, or of .iron and zinc, or a plurality of such alloys; and there maybe present a,

plurality of such intermediate alloy films, of various intermediate compositions.

Ve do vnot limit ourselves to the hot processes of 'applying zinc coatings, known to the hart, but we 'may also use the electrogalvani-cprocess, or this process in combination with subsequent hot process. This is shown in Fig. Y, Where the bath is an electro-galvanic incplating bath of any convenient type, and the bath 16 is a bath of molten zinc for the hot-process application of a zinc coating. However We prefer the hot process alone, because of thel attendant advantage we secure in the contemporaneous annealing action on the steel coating and the iron--base body and their .intermediate film of alloy.v By the term hot process -ofzinc coating We mea-n any of the kno-Wn processes forapplying'zinc coat-ings which are dependent upontheI application of heat to the ar, ticle to be coated and to. the ycoating material, including the use of cleaning .and/or luxingmaterials 17 and 18 for preparative purposes; and the usefof, neutral` and/or reducing gases or atmospheres for the purpose of enveloping the iron-base body, or said body in combinati-on with its steel coating, While in hot condition, and thusretarding or vpreventing surface oxidation of the same.

We do not limit ourselves to any oneprocess for applying the coating of steel to the iron-base body, but We may use any known process for this purpose or suitable modication of known processes for coating one metal with another in the hot .state of o-ne or'both. For example, as shown in Fig. 3,

We can use the process of casting molten steel 20 around an ingot or bar of iron 21 which has been lsuitably cleaned, iuxed, preheated and inserted in a suitable mold 22 of such dimensions With :respect to the iron bar or ingot as to obtain, a substantially uniform thin coatingl of steel enveloping the iron except at .the supportingcontacts 23 between tubular coating or.jacket 20coveri-ng the outer curved surface of the iron body. We cany also, as shown -in Fig. 4, take a thinrtube 24 of steeland suitably clean, flux and preheat it for use as the lining of., a mold 25 to receive molteniron 26; and then pour molten iron into the interior of said mold until full, so that the iron will adhere to the inner surface ofthe lining 24 of .the mold and when solidified become a single integral body.- Thesteel-coated .iron-base ingots, billets, or bars'thus produced may be hotrolled intol rodsl and cold-drawn into VWire by familiar processes in t-he art which. require no detailed description, but lare indicated diagrammatically in Fig. 7;v or the steel-coated bars may be rolled into sheets, or hot-fabricated into pipes, by methods familiar to the arts; other yshapes or products may manufactured from these steel-coated ironfbase bars, but in all theV examples just citedit 1s intended that the ultimate prodbase body in a bath of molten steel 30; and

in thel example of rods o-r Wire 3l the process may be Worked 1n continuous operation, as l illustrated in Fig. 6. In the hot-dipping process, the iron-base body is suitably cleaned, fluxed and preheated, by Well-known means, before dipping, so `as to promote the alloying of the molten steel with the surface metal of the iron-base body and also for the purpose of promoting the adherence of an outer film of hot steel upon Withdrawing the iron-base body from the molten bath. We prefer the method, illustrated in Fig. 5, of dipping the iron-base body 32, When in the form of an ingot,pbillet, bar, or rod, before subjecting the 'same to the process of cold Working, such as cold rolling or cold drawing; and before hot-fabricating Isuch billets or bars into pipe or other products requiring hot-Working `processes to manufact-ure them into final shape and size.

When the hot-dipping process is employed to steel-coat an ironebase body for manufacture linto zinc-coated wire, the steel-coated-V billet 32, ory steel-coated bar, for example, may be then hot-rolled into rods 33 and next cold-drawn into Wire 34; and' subsequently coated with zinc; `as is illustrated in Fig. 7.

or so-called `combined-carbon; small quan' tities of manganese and silicon are also usually present, and traces or slight impurities vconsisting of sulphur and phosphorus; in addition these steels sometimes' contain very small in edients of various non-ferrous metals. a' ded to the steel in the molten state for the purpose of deoxidizing it, or for im roving its molten fluidity, or for promoting the formation of stable compounds upon passing fromthe hot Huid state to the cold solid state, or for rendering the steel product more resistant to corrosion, or for improving the general properties of the steel product, such as manganese, silicon, aluminum, chromium, vanadium,

tungsten, nickel, copper, tin, titanium and rosion We may mention the so-called copperbearing steel which contains about onefourth of one per cent of copper. We recognize that the addition of substantial proportions of certain non-ferrous metals to' the kind of material which is predommant- L ly carbon-steel; for our purposes it would suiice even to use a crucible steel containing onlyr the elements iron and carbon, aside from substantially irremovable impurities.

We have not attempted to mention or dcscribe all of the known or possible processes for coating an iron or relatively low-carbon steel body with relatively high-carbon steel and our invention is not limited to those processes which we have mentioned or described, but embraces every method of producing such coating and subsequently applying a coating of zinc. Furthermore it is not essential, in our invention, to obtain a coating of steel which is substantially thick, but the steel coating may be as thin as practicable, or, at the minimum, of the order of thickness of the intervening alloy films before described, which is the result that we prefer. our invention, at what stage in the process as a whole the steel coating is applied, so long as it is applied before( the coating of zinc is applied; and it is not necessarily a detriment to our product if the steel coating is applied ,two or more times, either in succession or not, or whether at thesa-me stage or at different stages in the manufacture, but we prefer a single steel coating as suflicient to attain our result, and We also prefer, in the example of wire, to apply the steel coating before the operation of colddrawing or else in the early stages of drawing, and especially by casting the iron or low-carbon steel in a relatively high-carbon steel tube. 'A

We claim as our invention l. A zinc-coated iron or steel article, comprising an iron or low-carbon steel body;

and a plurality of separately applied coatings, thereon, including a coating of zinc,l and a coating of steel interposed between the z'inc coating and the s'aid body and of relatively high carbon content.

2. Zinc-coated iron or steel wire, com'- prising aniron or low-carbon steel core ;4 and a plurality of separately applied coatings thereon, including a coating of zinc, and a coating of stee interposed between thezinc coating and the said core and of relatively high carbon content. Y

3. A zinc-coated iron or steel article, comprising an iron-base body having arelatively low carbon content, an iron-base It is also immaterial, in`

jacket or 4coating upon and adhering to saidv body and having' a relatively high carbon content and an outer coating of zinc upon 'and adhering to said iron-base jacket or coating. f-

`Il. Zinc-coated iron or steel wire, comprising an iron-base core havinga relatively low carbon content, an iron-base jacket or coating upon and adhering to said core and having a relatively high carbon content, and an outer coating of zinc upon and adhering to said iron-base jacket or coating. l

5.-The process of making zinc-coated `wire, comprising making 4a relatively lowcarbon iron-base core; and separatelyjapplying a plurality of adhering coat-ings thereon, including applying a relatively high-carbon iron-base coating as a binder and later applying a zinc-coating, so that the first coating serves to improve the bond between the core and the zinc coating.

6. The process of making zinc-coated iron-base wire, Vcomprising rolling the rods from iron-base ingots of relatively low carbon content, drawing the wire from such rods; incasmg the wire stock at any desired time in an lntegrally adhering layer of iron-base material of relatively high car bon content as a binder; and applying a zinc coating to theincased wire, so that the binder layer serves to improve the bond of the zinc coating to the wire.

7. The process of making zinc-coated iron-base Wire, comprising pouring ingots of iron or low-carbon steel in a tube of relatively high-carbon steel so that the tube forms an integrally adhering binder jacket or coat-ing for the ingot; vrolling-the ingot into rods and drawing the rods into wire;

applying an integrally adhering iron-base binder jacket or coating of relatively high carbon content to the wire stock before it is reduced to the rod size, so that subsequent rolling will act on said jacket or coatas well as on the wire stock Within it;

in susequently drawing the wire from the rod; and applying a zinc coating to the wire, so that the binder jacket. or coating serves to improve the bond 4'of the zinc coating to the wire.

9. The process of making aizinc-coated article, Icomprising forming a core of iron or low-carbon steel; incaslng said core in an integrally adhering iron-base binder jacket or coating of relatively vhigh carbon Acontent at any desired stage in its manufacture; and subsequently applying a. zinc- 'and applying a. zinc-coating to the'- wire so ing to the core.

coating uponsuch y iron-base coating or jacket, so that the bmd'er jacket or coating serves to improve the bond of the zinc coat- 10. The process of making a zinc-coated iron-basearticle, comprising casting an ingot of iron or low-carbon steel in a tube of relatively high-carbon steel so that the tube forms an integrally adhering binder coating or jacket for saidingot; operating on said ingot to increase its length and reduce its crossfsection to desired shape and size; and applying a zinc-coating upon the article, so that the binder jacket or coating serves to improve the bond of the zinc coating t0 the iron-base article. A

11. The process of making an iron-base article, comprising casting an ingot of iron or relatively low-carbon steel; coating said ingot with a layer of relatively high-carbon metal to lsaid article, so that the binder layer servies-to improve the bond of the non-ferrous metal to the iron-base article- In Witness whereof, "We have hereunto setour; hands at Washington, D. C., this 18th day of December, A. D. one thousand nine hundred and twenty-three.

FRANK F. FOWLE. FREDERICK M. CRAPO. 

